This disclosure relates to batteries. In particular, this disclosure relates to batteries with a coating that serves as a safety coating and provides pressure-sensitive conduction.
Billions of button batteries (also known as button cells) are sold each year to power portable electronic devices including, for example, small PDAs, musical greeting cards, glucometers, watches, virtual pet devices, hearing aids, and laser pointers. Tragically, accidental ingestion of these small batteries caused more than 40,400 children under the age of 13 to visit hospital emergency rooms, with 14 battery-related deaths in children 7 months to 3 years of age between 1997 and 2010 in the United States alone. As manufacturers create more powerful button batteries in smaller casings, button battery ingestion and injury is on the rise, and the increase in battery power yields a corresponding increase in severity of injuries and mortality resulting from button battery ingestion. Though safety standards now regulate locked battery compartments in toys, minimal technological development has taken place at the level of the battery to limit injury, particularly batteries in the greater than or equal to 20 millimeter format which are recognized as leading causes of complications if ingested. In addition to children, especially those under the age of five, an increasing number of seniors ingest button batteries after mistaking the button batteries for pills, particularly as button batteries are ubiquitous in devices used frequently by seniors, such as hearing aids. Furthermore, countless pets ingest button batteries each year.
Gastrointestinal (GI) obstruction is typically the first clinical symptom of button battery ingestion. However, button battery ingestion is more severe than ingestion of comparably sized objects, such as coins, due to damage by short circuit currents. Current flow in conductive GI fluids can cause electrolysis, generate hydroxide ions, and create long-term tissue damage in the digestive tract. Short circuiting of ingested button batteries has caused acute injuries including esophageal and GI perforations, trachea-esophageal fistulae, arterio-esophageal fistula leading to death, esophageal stenosis/stricture, chemical burns, as well as vocal cord paralysis. Case studies have shown that GI perforation in humans can occur as soon as five hours after battery ingestion. In pets, severe GI damage occurs even more quickly, with reports of transmural esophageal necrosis within one hour of ingestion in dogs and within two to four hours in cats.
Additionally, the short circuit current can damage the polymer gasket that separates the anode and cathode. Once the gasket is impaired or compromised, the contents of the button battery, including toxic metals such as cadmium, lead, mercury and lithium, may be released into the body. The release of button battery contents poses both the acute and long-term health risks associated with heavy metal ingestion.